Modern aircraft typically include a great number of sensors, effectors (e.g. actuators), etc., connected to an avionics network having one or more central processors. The sensors, effectors, etc. are typically line replaceable units (LRUs) to improve operational effectiveness. The LRUs are typically concentrated at particular locations in the aircraft where systems are installed. To reduce wiring, and therefore weight, a remote data concentrator (RDC) may be used to connect several of the LRUs to the avionics network.
To reduce design and manufacturing costs, and to improve operational effectiveness, all of the RDCs on a particular aircraft may be standardised, regardless of the LRUs to which they are connected. The RDCs may therefore have common hardware, and so are known as common remote data concentrators (cRDCs). The cRDCs may include configurable software. Standardisation of the cRDC makes it possible to hold an inventory of fewer parts, such that a defective cRDC can be readily replaced during routine maintenance tasks, thereby improving operational effectiveness.
During normal operation, a signal between the LRU and the remote processor may be routed via the RDC and over the avionics network. In the event of failure in transmitting the signal over this primary network, the LRU may additionally be connected to the remote processor via a secondary control system, avoiding the RDC and the primary network, so as to provide redundancy. This secondary control system adds additional complexity and weight, but is deemed necessary as the RDC is essentially a “dumb” data concentrator that simply converts one signal into another.